溅射功率对LiCoO2薄膜结构及性能的影响研究

The Effects of Sputtering Power on the Structure and Properties of LiCoO_(2) Thin Films

采用射频磁控溅射技术,在不锈钢衬底上沉积制备了(003)取向的LiCoO_(2)薄膜。通过X射线衍射仪、扫描电镜、拉曼及电化学测试探究了溅射功率对LiCoO_(2)薄膜结构及电化学性能的影响。结果表明在80-160 W功率范围内,适当增加功率有助于Co与O的键合,提高薄膜的结晶度。功率为120 W时,首次放电比容量为40.9μAh cm-2μm-1,循环100圈后容量保持率为61.2%;但当功率提高到160 W时,由于过快的沉积速率难以与粒子在衬底表面的扩散速率相匹配反而会造成LiCoO_(2)结晶度下降,晶格产生畸变,阻碍了Li+在材料内部的扩散,循环100圈后容量保持率只有54.2%。

LiCoO_(2) thin films with(003) orientation were deposited on stainless steel foil by magnetron sputtering. And the influence of power on the structure and electrochemical properties of LiCoO_(2) thin films were investigated by XRD, SEM, Raman and electrochemical tests. Results indicate that in the range of 80~160 W, an appropriate increase of power is conducive to the bonding of Co and O atoms, which further improves the crystallinity of the films. When the power is 120 W, LiCoO_(2) displays an excellent initial discharge specific capacity of 40.9 μAh cm-2μm-1and with a capacity retention of 61.2% through 100 cycles. However, when the power is increased to 160 W,the lattice and crystallinity of LiCoO_(2) will be compressed because the rapid deposition rate is difficult to match the diffusion rate of particles on the substrate surface. It blocks the diffusion of lithium ions inside LiCoO_(2), and the capacity reduces to 54.2% after 100 cycles.